1. Field of the Invention
The present invention relates to a system and method for handling and processing semiconductor wafers and, in particular, to a load lock apparatus with an integrated staging shelf and an auxiliary module.
2. Description of the Related Art
In the processing of semiconductor devices, such as transistors, diodes, and integrated circuits, a plurality of such devices are fabricated simultaneously on a thin slice of semiconductor material, termed a substrate or wafer. When manufacturing these devices, it is imperative that the wafer does not become contaminated by particulate. Accordingly, wafer processing systems typically include a load lock apparatus that provides a substantially particle free environment from which wafers may be selectively withdrawn by a wafer handling assembly for placement into one or more processing modules.
To further improve the quality of wafer processing, it may be advantageous to pre-clean or measure the wafer before the wafer is processed in a process module. If such pre-cleaning or measuring is desired, an auxiliary module can be added to an existing wafer processing station. There are, however, several disadvantages associated with adding an auxiliary module to an existing wafer processing station. For example, adding an auxiliary module to an existing wafer processing station typically increases the footprint of the wafer processing station. Moreover, the auxiliary module also typically requires additional handling of the wafers and/or modifications to the wafer handling assembly. Furthermore, the addition of the auxiliary module typically decreases the throughput of the processing station. For example, in a cluster type processing station, one or more of the processing modules may have to be replaced. Similarly, in a stand alone type processing station, adding a pre-cleaning or measuring process typically increases the amount of time that a wafer is in a particular processing station.